Screening mammography is the primary imaging modality for early detection of breast cancer because it is the only method of breast imaging that consistently has been found to decrease breast cancer-related mortality [1-3]. Mammography may detect cancer one and a half to four years before a cancer becomes clinically evident [4,5].
The prototype of the mammography unit was developed in 1965 . Many technical advances have been made since then to improve the image quality, as well as to reduce the radiation dose to the patient. Ongoing technologic advancements, to both enhance mammography and develop other breast imaging modalities, seek to provide earlier diagnosis of breast disease; more accurate assessment of disease extent and treatment response; and improve the detection of recurrence.
This topic will review mammography technique, performance capabilities of mammography in particular patient groups, interpretation of a mammogram report, and the use of breast ultrasound as an adjunct to mammography. Newer mammography techniques are also discussed. Issues regarding screening for breast cancer, the role of mammography in women with suspected disease, and surveillance for patients with known breast cancer are discussed separately (see "Screening for breast cancer: Strategies and recommendations" and "Clinical features, diagnosis, and staging of newly diagnosed breast cancer" and "Approach to the patient following treatment for breast cancer"). Other imaging techniques for breast disease are discussed separately. (See "MRI of the breast and emerging technologies".)
THE MAMMOGRAPHIC EXAMINATION
A mammogram involves exposing the breast to x-rays. These x-rays are both transmitted through the breast tissue as well as scattered to the surrounding tissue. The x-rays are attenuated based upon the characteristics of the breast tissue, and are then absorbed as latent images on the recording device (figure 1). The latent image is processed and displayed for diagnostic purposes .
Routine evaluation includes obtaining two views (craniocaudal and mediolateral oblique) of each breast. In the craniocaudal (CC) view (image 1), the breast is lifted and positioned on the plate and compression is applied from above. In the mediolateral oblique (MLO) view (image 2), the breast is compressed and imaged from the side. Breast positioning is critical. Improper positioning may lead to exclusion of parts of the breast from the field of view, risking non-visualization of a cancer (image 3).